1. Field of the Invention
The present invention relates to a camera system having a camera body and a photographing lens which is detachably attached to the camera body, and having a communication system between the camera body and the photographing lens, wherein a rear converter can be mounted between the camera body and the photographing lens.
2. Description of the Related Art
In conventional interchangeable lens cameras, the camera body obtains fundamental information on the photographing lens via predetermined data communication performed between the camera body and the photographing lens. However, if a rear converter is mounted between the camera body and the photographing lens, the data communication cannot be performed, so that it is impossible to use any useful features that the photographing lens may possess.
Even if the rear converter is simply provided with relay channels for connecting each communication channel of the camera body with a corresponding connecting channel of the photographing lens, the camera body cannot recognize the existence of such rear converter, so that the camera body cannot control operations of the photographing lens properly with only data received from the photographing lens. In addition, if the camera body is provided with additional electrical contacts for data communications between the camera body and the rear converter, the camera body needs to be provided with one or more additional components for the additional electrical contacts, and also switching between the communication channels becomes necessary, complicating the structure of the camera system.
The present invention provides a communication system between a camera body and a photographing lens of a camera system, wherein a rear converter can be mounted between the camera body and the photographing lens, and data on the rear converter can be used without any complicated structure.
For example, in an embodiment, an interchangeable lens camera system having a camera body, a photographing lens, and a rear converter which can be mounted between the camera body and the photographing lens, is provided, the camera body having a first group of contacts, the photographing lens having a second group of contacts, the camera body and the photographing lens communicating with each other via the first group of contacts and the second group of contacts with the first group of contacts being electrically connected with the second group of contacts, respectively, wherein the rear converter includes a group of relay channels via which the first group of contacts of the camera body are electrically connected with the second group of contacts of the photographing lens, respectively, in a state where the rear converter is mounted between the camera body and the photographing lens; a rear converter memory in which rear converter data on the rear converter is stored, the rear converter memory including at least one port electrically connected to corresponding at least one relay channel of the group of relay channels; and a rear converter controller which controls a reading operation of the rear converter data from the rear converter memory, the rear converter controller including at least one port electrically connected to corresponding at least one relay channel of the group of relay channels. The rear converter memory and the rear converter controller have a function to send the rear converter data to the camera body while the camera body and the photographing lens communicate with each other via the first group of contacts, the second group of contacts, and the group of relay channels.
It is desirable for the photographing lens to include a lens memory in which photographing lens data is stored; wherein the camera body includes a body controller which communicates with the lens memory to read the photographing lens data from the lens memory; wherein a portion of the photographing lens data serves as dummy data for the rear converter; and wherein the rear converter data is read out of the lens memory to be transmitted to the body controller in synchronization with an operation of the body controller in which the body controller receives the dummy data.
The body controller can be electrically connected to the rear converter controller via a first communication/control contact of each of the first group of contacts and the second group of contacts, and a data I/O contact of each of the first group of contacts and the second group of contacts. The photographing lens can include a lens controller which communicates with the body controller. The body controller is electrically connected to the lens controller via the first communication/control contact, a second communication/control contact of each of the first group of contacts and the second group of contacts, and at least one relay channel of the group of relay channels, wherein a handshake operation is performed between the body controller and the lens controller via the second communication/control contact. The lens controller sends out dummy data to enable the data I/O contact if inputting a command for the rear converter, which is issued by the body controller, via the data I/O contact, while the lens controller communicates with the body controller. The rear converter sends out the rear converter data to the data I/O contact in the case where the command is input via the data I/O contact.
In an embodiment, the rear converter receives the dummy data from the lens controller in the case where the lens controller receives the command; and the rear converter sends the rear converter data to the body controller in synchronization with an operation of the body controller in which the body controller receives the dummy data.
The body controller can be set to recognize one of a last one byte and a last few types of the photographing lens data as the dummy data for the rear converter.
In another embodiment, a rear converter which can be mounted between a camera body and a photographing lens of an interchangeable lens camera system, is provided, the camera body having a first group of contacts, the photographing lens having a second group of contacts, the camera body and the photographing lens communicating with each other via the first group of contacts and the second group of contacts with the first group of contacts being electrically connected to the second group of contacts, respectively, wherein the rear converter includes a group of relay channels via which the first group of contacts of the camera body are electrically connected with the second group of contacts of the photographing lens, respectively, in a state where the rear converter is mounted between the camera body and the photographing lens; a rear converter memory in which rear converter data is stored, the rear converter memory including ports electrically connected to at least one relay channel of the group of relay channels; and a rear converter controller which controls a reading operation of the rear converter data from the rear converter memory, the rear converter controller including ports electrically connected to at least one relay channel of the group of relay channels. The rear converter memory and the rear converter controller have a function to send the rear converter data to the camera body while the camera body and the photographing lens communicate with each other via the first group of contacts, the second group of contacts, and the group of relay channels.
Each of the first group of contacts and the second group of contacts can include a first communication/control contact via which the body controller sends a control signal to the lens controller; a second communication/control contact via which the lens controller sends a control signal to the body controller; and a data I/O contact for data communication. The first communication/control contact, the second communication/control contact, and the data I/O contact of the first group of contacts are electrically connected to the first communication/control contact, the second communication/control contact and the data I/O contact of the second group of contacts, respectively, via the group of relay channels. The rear converter memory and the rear converter controller are electrically connected to relay channels of the group of relay channels which correspond to the first communication/control contact and the data I/O contact. The rear converter memory and the rear converter controller have a function to send the rear converter data to the camera body after a commencement of a handshake operation between the body controller and the lens controller via the second communication/control contact in the case where the camera body commands the rear converter controller to send the rear converter data via the data I/O contact.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2001-54543 (filed on Feb. 28, 2001) which is expressly incorporated herein by reference in its entirety.